Introduction. All projects in this proposal will use the administrative core. We will maintain the basic organization of the Center for Perinatal Biology which has developed during the past two decades. This structure has grown out of the close scientific collaboration among the investigators in our group. This overall organization includes the core facilities for administrative and laboratory services, and an objective evaluation of our scientific progress both quarterly and annually. We will administer the program as efficiently as possible, so that the maximum amount of each investigator's time can be devoted to the research per se.